Load Preset and execute Function or Operator
If its written in python can be found with a little digging.
The key here is in the menu, you are defining which operator to use to execute presets
    preset_operator = &quot;script.execute_preset&quot;

If we can find it in bpy.types then it has a python module
&gt;&gt;&gt; bpy.ops.script.execute_preset.idname()
'SCRIPT_OT_execute_preset'

&gt;&gt;&gt; bpy.types.SCRIPT_OT_execute_preset.__module__
'bl_operators.presets'

and there it is in 2.91/scripts/startup/bl_operators/presets.py
class ExecutePreset(Operator):
    &quot;&quot;&quot;Execute a preset&quot;&quot;&quot;
    bl_idname = &quot;script.execute_preset&quot;
    bl_label = &quot;Execute a Python Preset&quot;

    filepath: StringProperty(
        subtype='FILE_PATH',
        options={'SKIP_SAVE'},
    )
    menu_idname: StringProperty(
        name=&quot;Menu ID Name&quot;,
        description=&quot;ID name of the menu this was called from&quot;,
        options={'SKIP_SAVE'},
    )

    def execute(self, context):
        from os.path import basename, splitext
        filepath = self.filepath

        # change the menu title to the most recently chosen option
        preset_class = getattr(bpy.types, self.menu_idname)
        preset_class.bl_label = bpy.path.display_name(basename(filepath))

        ext = splitext(filepath)[1].lower()

        if ext not in {&quot;.py&quot;, &quot;.xml&quot;}:
            self.report({'ERROR'}, &quot;unknown filetype: %r&quot; % ext)
            return {'CANCELLED'}

        if hasattr(preset_class, &quot;reset_cb&quot;):
            preset_class.reset_cb(context)

        if ext == &quot;.py&quot;:
            try:
                bpy.utils.execfile(filepath)
            except Exception as ex:
                self.report({'ERROR'}, &quot;Failed to execute the preset: &quot; + repr(ex))

        elif ext == &quot;.xml&quot;:
            import rna_xml
            rna_xml.xml_file_run(context,
                                 filepath,
                                 preset_class.preset_xml_map)

        if hasattr(preset_class, &quot;post_cb&quot;):
            preset_class.post_cb(context)

        return {'FINISHED'}

re-write another operator, using same properties,  to do whatever floats your boat when your preset is loaded, and tell the system to use it instead
preset_operator = &quot;script.execute_preset_float_boat_version&quot;

Ok, since we are no longer using the default operator, we can set the defaults for the operator in the draw preset method of menu class
&gt;&gt;&gt; bpy.types.Menu.draw_preset(
draw_preset(self, _context)
Define these on the subclass:
- preset_operator (string)
- preset_subdir (string)
Optionally:
- preset_add_operator (string)
- preset_extensions (set of strings)
- preset_operator_defaults (dict of keyword args)

Define the callbacks
Looking at the operator code, notice two callback functions are run, one before the preset is loaded reset_cb and one after post_cb.  Have added these two classmethods to Menu to print to console when called.
so in full
import bpy
from bpy.types import Operator, Menu
from bl_operators.presets import AddPresetBase
from bpy.props import StringProperty

class ExecutePreset(Operator):
    &quot;&quot;&quot;Execute a preset&quot;&quot;&quot;
    bl_idname = &quot;script.execute_preset_float_boat&quot;
    bl_label = &quot;Execute a Python Preset&quot;

    filepath: StringProperty(
        subtype='FILE_PATH',
        options={'SKIP_SAVE'},
    )
    menu_idname: StringProperty(
        name=&quot;Menu ID Name&quot;,
        description=&quot;ID name of the menu this was called from&quot;,
        options={'SKIP_SAVE'},
    )

    def execute(self, context):
        from os.path import basename, splitext
        filepath = self.filepath

        # change the menu title to the most recently chosen option
        preset_class = getattr(bpy.types, self.menu_idname)
        preset_class.bl_label = bpy.path.display_name(basename(filepath))

        ext = splitext(filepath)[1].lower()

        if ext not in {&quot;.py&quot;, &quot;.xml&quot;}:
            self.report({'ERROR'}, &quot;unknown filetype: %r&quot; % ext)
            return {'CANCELLED'}

        if hasattr(preset_class, &quot;reset_cb&quot;):
            preset_class.reset_cb(context)

        if ext == &quot;.py&quot;:
            try:
                bpy.utils.execfile(filepath)
            except Exception as ex:
                self.report({'ERROR'}, &quot;Failed to execute the preset: &quot; + repr(ex))

        elif ext == &quot;.xml&quot;:
            import rna_xml
            rna_xml.xml_file_run(context,
                                 filepath,
                                 preset_class.preset_xml_map)

        if hasattr(preset_class, &quot;post_cb&quot;):
            preset_class.post_cb(context)

        return {'FINISHED'}

class OBJECT_MT_display_presets(Menu):
    bl_label = &quot;Object Display Presets&quot;
    preset_subdir = &quot;object/display&quot;
    preset_operator = &quot;script.execute_preset_float_boat&quot;
    preset_operator_defaults = {
            &quot;menu_idname&quot; : 'OBJECT_MT_display_presets'
            }
    draw = Menu.draw_preset
    @classmethod
    def reset_cb(self, context):
        print(&quot;Reset&quot;)
    @classmethod        
    def post_cb(self, context):
        print(&quot;Post Callback&quot;)


class AddPresetObjectDisplay(AddPresetBase, Operator):
    '''Add a Object Display Preset'''
    bl_idname = &quot;camera.object_display_preset_add&quot;
    bl_label = &quot;Add Object Display Preset&quot;
    preset_menu = &quot;OBJECT_MT_display_presets&quot;

    # variable used for all preset values
    preset_defines = [
        &quot;obj = bpy.context.object&quot;
    ]

    # properties to store in the preset
    preset_values = [
        &quot;obj.display_type&quot;,
        &quot;obj.show_bounds&quot;,
        &quot;obj.display_bounds_type&quot;,
        &quot;obj.show_name&quot;,
        &quot;obj.show_axis&quot;,
        &quot;obj.show_wire&quot;,
    ]

    # where to store the preset
    preset_subdir = &quot;object/display&quot;


# Display into an existing panel
def panel_func(self, context):
    layout = self.layout

    row = layout.row(align=True)
    row.menu(OBJECT_MT_display_presets.__name__, text=OBJECT_MT_display_presets.bl_label)
    row.operator(AddPresetObjectDisplay.bl_idname, text=&quot;&quot;, icon='ZOOM_IN')
    row.operator(AddPresetObjectDisplay.bl_idname, text=&quot;&quot;, icon='ZOOM_OUT').remove_active = True


classes = (
    ExecutePreset,
    OBJECT_MT_display_presets,
    AddPresetObjectDisplay,
)


def register():
    for cls in classes:
        bpy.utils.register_class(cls)
    bpy.types.OBJECT_PT_display.prepend(panel_func)


def unregister():
    for cls in classes:
        bpy.utils.unregister_class(cls)
    bpy.types.OBJECT_PT_display.remove(panel_func)


if __name__ == &quot;__main__&quot;:
    register()